This invention generally relates to a vehicle seat. More particularly, the invention pertains to a seat slide device for slidably supporting a vehicle seat and fixing the position of a vehicle seat relative to the floor.
A known seat slide device is disclosed in Japanese Patent Laid-Open Publication No.10-315810. This known seat slide device is disposed between the seat and the floor of the vehicle, with shoes being interposed between an upper rail fixed to the seat and a lower rail fixed to the floor so that the upper rail is able to relatively smoothly slide on the lower rail. In the known device, rollers for supporting the load from the seat side are disposed between the upper rail and the lower rail, and the shoes are provided to prevent excessive play by a space provided to roll the rollers. When the load in an upward direction is applied to the seat slide device, small projections disposed on upper surfaces of the shoes are elastically deformed to prevent excessive play. On the other hand, when a load in the lateral direction is applied, excessive play is prevented by elastic deformation of the shoes.
However, with the known seat slide device which relies on elastic deformation of the small projections to prevent the excessive play when a load is applied in the upward direction, the known seat slide device cannot prevent play which exceeds a range of the elastic deformation of the small projection. To solve this drawback, it is necessary to manufacture each of the rails with relatively precise dimensions. As a result, the manufacturing cost increases.
Another way to prevent excessive play would be to increase the range of the bending amount of the small projections by enlarging the projections. However, a large bending amount would be recognized as excessive play by a passenger, and so the effect of the projections is reduced.
According to one aspect, a seat slide device mounted in a vehicle includes a lower rail supported on a floor of the vehicle, an upper rail slidably engaged with the lower rail and supporting a seat, and a shoe attached to an engaging portion provided at one of the lower rail and the upper rail. An engaged portion formed at the other of the lower rail and the upper rail to be engaged with the engaging portion through the shoe. The shoe includes a base portion attached to the engaging portion and a slide portion sliding with the engaged portion and integrally formed with the base portion, with the slide portion coming in contact with the base portion when a load applied to the slide portion exceeds a predetermined value. The base portion has a contact surface possessing a shape which increases the contact area with the slide portion when the load increases after reaching the predetermined value.
According to another aspect, a seat slide device adapted to be mounted in a vehicle includes a first rail and a second rail, with one of the rails being adapted to be secured on a floor of the vehicle and the other of the rails being adapted to support a seat, and with the rail which is adapted to support the seat being slidably engaged with the rail that is adapted to be secured on the floor of the vehicle. The seat slide device also includes a pair of shoes each having a base portion mounted at the first rail and a slide portion integrally formed in one piece with the base portion. The slide portion is positioned between the base portion and a part of the second rail and slidably engages the part of the second rail. The base portion and the slide portion of each shoe are configured so that an increasing load applied to the slide portion which exceeds a predetermined value causes an increase in the contact area between the slide portion and the base portion.
In accordance with a further aspect, a seat slide device which is adapted to be mounted in a vehicle includes first and second rails, one of which is adapted to be secured on a floor of the vehicle and the other of which is adapted to support a seat, with the rail which is adapted to support the seat being slidably engaged with the rail that is adapted to be secured on the floor of the vehicle to adjust the position of the seat. The seat slide device also includes a plurality of rollers positioned between the first and second rails, and a pair of shoes. Each of the shoes includes a base portion mounted at the first rail and a slide portion integrally formed in one piece with the base portion. The slide portion is positioned between the base portion and a part of the second rail, and slidably engages the part of the second rail. Both the slide portion and the base portion have surfaces facing one another. The base portion and the slide portion have a configuration such that in the absence of a load applied to the slide portion which exceeds a predetermined value the surface of the slide portion is out of contact with the surface of the base portion, and in the presence of a changing load applied to the slide portion which exceeds the predetermined value the surface of the slide portion contacts the surface of the base portion with a contact area between the surface of the slide portion and the surface of the base portion varying.